Particular aspects of crystallization have been noted in some emeralds of Muzo, namely crystals that in 1923 Scheibe deemed emerald gemelos or telescope. At first, it was believed that emerald transformations, following an in-depth study, definitively concluded that these crystals were typical of Muzo and formed by crystallization with a hexagonal carbon core that branched out into the periphery, dividing the emerald crystal into rays.
These crystals, which are considered unique of the species and characteristic of Muzo, make up specimens of mineralogical importance because they indicate the metamorphic formation of emeralds and undoubtedly serve to characterize this gem.
Around 1963 a farmer in a very small locality of Muzo, digging without difficulty between a large rocky area, established evidence of the existence of the original veins of these curious emeralds, which were then given the name of Trapiche in reference to their particular appearance similar to the outer sprockets of the sugar cane grinding mill, called Trapiche.
The locality of these veins is very close to the Muzo mines, the mentioned Pena Blanca and the same geological layer;
In the Trapiche of P. Blanca, the center of the crystal is tapered, it grows relatively quickly in the first phase and the growth comes from a hydrothermal solution containing a considerable amount of albite (feldspar). A likely sudden change in conditions started a short transition period with the result of simultaneous precipitation of emerald and albite; this produced a hexagonal outline outside the centre of the crystal.
For the Trapiche of Muzo, the mechanism of growth appears, in some respects clearly contrary to those of P. Blanca. In the first stage the growth was sufficiently fast to the point of uniformly grouping carbonaceous material into the centre of the hexagonal prism. A rapid decrease in growth was also found in the same conditions of growth as P. Blanca stratified, but with carbonaceous material grouped at the corners.
The trapped emeralds, whether they are from Muzo or P. Blanca, therefore have a radial alignment system that runs along the length of the crystal itself and flows into the ends of the crystal in a hexagonal centre. The material of the rays consists of an excellent emerald, while the green-greyish and blackish is similar to the material that often accompanies the emerald in the mines and locally called the morale.
For P. Blanca’s Trapiche in the X-ray diffractive examination, it was revealed that white-gray areas are made up of albite and emeralds, and what is surprising is that the part of this measure is perfectly aligned, bordering with the part of the emerald. In other words the entire Trapiche of the emerald is a single crystal simply containing, in certain regions, large quantities of albite.
In the Trapiche of Muzo the centre (namely the heart) is black and from it black arms start. The black material is as hard as the green (emerald) and differs from that of P. Blanca which is white-grey and softer.
In examining this black material from the Trapiche of Muzo it has been found to contain many amounts of carbon substances, such as the common inclusions of the emeralds of Muzo in general; All is derived from the clay, coal-like, associated with dolomite, calcite, pyrite, etc.
Even for Muzo’s Trapiche, X-ray diffraction analysis have confirmed to the aforementioned researchers that they are single crystals.